The success of service-based applications is based on service technologies such as Web services. Nevertheless, the benefits of the Service-Oriented Architecture (SOA) remain mainly at the software level, since business people are often unable to fully exploit its benefits due to their unfamiliarity with such software level technology. The intentional Service-Oriented Architecture (iSOA) suggests a move from the function-driven SOA to intention-driven SOA in order to provide service description understandable by business practitioners. However, such transposition from business to implementation level should also consider Quality of Service (QoS) aspects. In this paper, we propose modeling the Quality of intentional Service (QoiS) by introducing the quality goals and their qualitative and quantitative evaluation. We also propose populating the intentional service registry of the iSOA architecture with the QoiS description.